The larvae of these beneficial insects are also called "aphid lions" due to their voracious appetite for aphids, lace bugs, small caterpillars, and many other insects. They are similar in shape to ladybug larvae but are light brown and have a pair of large, curved mandibles for capturing their prey.
Photos:
Larva: Whitney Cranshaw, Colorado State University, Bugwood.org
Adult: Joseph Berger, Bugwood.org